The antibacterial arm of the Drosophila innate immune response requires anI kappa B kinase

The ird5 gene was identified in a genetic screen for Drosophila immune resp onse mutants. Mutations in ird5 prevent induction of six antibacterial pept ide genes in response to infection but do not affect the induction of an an tifungal peptide gene. Consistent with this finding, Escherichia coli survi ve 100 times better in ird5 adults than in wild-type animals. The ird5 gene encodes a Drosophila homolog of mammalian I kappaB kinases (IKKs). The ird 5 phenotype and sequence suggest that the gene is specifically required for the activation of Relish, a Drosophila NF-kappaB family member.